Typically, display devices capable of displaying stereoscopic (three-dimensional) images have been proposed. Moreover, there has been a demand for enabling selective display of two-dimensional (2D) images and three-dimensional (3D) images using the same display device. In order to meet that demand, a 2D/3D switching technology has been proposed.
Furthermore, a 3D display has also been proposed in which a plurality of lenses having the 2D/3D switching functionality is placed one upon another and which enables selective switching of the 3D display of each lens. For example, a technology is known in which two liquid crystal lens arrays having different focal point distances are placed one upon another and which enables switching between the numbers of parallaxes and between visible area angles. In this technology, each of the two types of liquid crystal lenses can switch between 2D display and 3D display due to ON/OFF control of the voltage applied thereto. Of the two types of liquid crystal lenses, the voltage to be applied to one liquid crystal lens is turned to the ON state and the voltage to be applied to the other lens is turned to the OFF state. With that, it becomes possible to achieve two types of 3D displays having different focal point distances.
However, in the technology described above, since it is necessary to have two layers of liquid crystal lens arrays, it results in an increase in the manufacturing cost. Moreover, since there is an increase in the thickness of the lens portion, the luminance undergoes a decline. In that regard, it is an object of the present invention to provide an image display device that enables switching between the numbers of parallaxes and between visible area angles while curbing an increase in the thickness of the lens portion.